Pentobarbital-induced narcosis may be reversed by intraseptal injection of bicuculline, thyroid-releasing hormone and kainic acid. Moreover pentobarbital produces a dose dependent decrease in the turnover rate of acetylcholine in cortex and hippocampus but not in striatum. The decrease in hippocampus may be reversed by slow infusion into septum of bicuculline, thyroid releasing hormone and kainic acid. The data suggest that the antagonism of the pentobarbital induced decrease in acetylcholine turnover and the narcosis may be modulated through an action on the gamma-aminobutyric acid interneurons in the lateral septum.